Overexposure to UV rays originating from the sun (light rays of wavelength shorter than approximately 3800 angstroms) will cause human skin damage and is generally believed to be the leading cause of various types of skin cancer. UV intensity (UVI) varies according to a number of factors, including cloud cover, season, time of day, altitude, latitude and the thickness of ozone layer. The impact of UV rays on the human skin also varies according to a number of factors, including the UVI, the duration of exposure and the application of sun protection.
Although various types of UVI monitors are known, the complexity of design, size, cost and the need of a power source have restricted their use to specific scientific procedures. Simpler monitors do not provide any indication to the users how long they can safely stay in the sun or how that time may be lengthened through the use of a sun protection product.
It would be desirable to have a pocket size, inexpensive, self-powered and easy to use UVI monitor which would enable people to tell how long they could safely stay in the sun on any particular day and, if a sun protection product is used, how that time may be lengthened on the basis of the SPF value selected. Alternatively, such a monitor would enable people to chose a sun protection product having a SPF value required for a given duration of exposure to the sun. The present invention provides such a UVI monitor.